Hi,
On 9/15/2023 2:14 AM, Nathan Chancellor wrote:
> Hi Hou,
>
> On Fri, Sep 08, 2023 at 09:39:22PM +0800, Hou Tao wrote:
>> From: Hou Tao <houtao1@xxxxxxxxxx>
>>
>> Add extra check in bpf_mem_alloc_init() to ensure the unit_size of
>> bpf_mem_cache is matched with the object_size of underlying slab cache.
>> If these two sizes are unmatched, print a warning once and return
>> -EINVAL in bpf_mem_alloc_init(), so the mismatch can be found early and
>> the potential issue can be prevented.
>>
>> Suggested-by: Alexei Starovoitov <ast@xxxxxxxxxx>
>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
>> ---
>> kernel/bpf/memalloc.c | 33 +++++++++++++++++++++++++++++++--
>> 1 file changed, 31 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
>> index 90c1ed8210a2..1c22b90e754a 100644
>> --- a/kernel/bpf/memalloc.c
>> +++ b/kernel/bpf/memalloc.c
>> @@ -486,6 +486,24 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
>> alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false);
>> }
>>
>> +static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
>> +{
>> + struct llist_node *first;
>> + unsigned int obj_size;
>> +
>> + first = c->free_llist.first;
>> + if (!first)
>> + return 0;
>> +
>> + obj_size = ksize(first);
>> + if (obj_size != c->unit_size) {
>> + WARN_ONCE(1, "bpf_mem_cache[%u]: unexpected object size %u, expect %u\n",
>> + idx, obj_size, c->unit_size);
>> + return -EINVAL;
>> + }
>> + return 0;
>> +}
> I am seeing the warning added by this change as commit c93047255202
> ("bpf: Ensure unit_size is matched with slab cache object size") when
> booting ARCH=riscv defconfig in QEMU. I have seen some discussion on the
> mailing list around this, so I apologize if this is a duplicate report
> but it sounded like the previously reported instance of this warning was
> already resolved by some other changeor supposed to be resolved by [1].
> Unfortunately, I tested both current bpf master (currently at
> 6bd5bcb18f94) with and without that change and I still see the warning
> in both cases. The rootfs is available at [2], if it is relevant.
Thanks for the report. It seems it is a new problem which should be
fixed by commit d52b59315bf5 ("bpf: Adjust size_index according to the
value of KMALLOC_MIN_SIZE"), but failed to. However I could not
reproduce the problem by using the provided steps. Do you configure any
boot cmd line in your local setup ? I suspect dma_get_cache_alignment()
returns 64 of 1 in your setup, so slab-96 is rounded up to slab-128.
Could you please run the attached debug patch and post its output ?
> $ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux- mrproper defconfig Image
>
> $ qemu-system-riscv64 \
> -display none \
> -nodefaults \
> -bios default \
> -M virt \
> -append earlycon \
> -kernel arch/riscv/boot/Image \
> -initrd riscv-rootfs.cpio \
> -m 512m \
> -serial mon:stdio
> ...
> [ 0.000000] Linux version 6.5.0-12679-gc93047255202 (nathan@dev-arch.thelio-3990X) (riscv64-linux-gcc (GCC) 13.2.0, GNU ld (GNU Binutils) 2.41) #1 SMP Thu Sep 14 10:44:41 MST 2023
> ...
> [ 0.433002] ------------[ cut here ]------------
> [ 0.433128] bpf_mem_cache[0]: unexpected object size 128, expect 96
> [ 0.433585] WARNING: CPU: 0 PID: 1 at kernel/bpf/memalloc.c:500 bpf_mem_alloc_init+0x348/0x354
> [ 0.433810] Modules linked in:
> [ 0.433928] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-12679-gc93047255202 #1
> [ 0.434025] Hardware name: riscv-virtio,qemu (DT)
> [ 0.434105] epc : bpf_mem_alloc_init+0x348/0x354
> [ 0.434140] ra : bpf_mem_alloc_init+0x348/0x354
> [ 0.434163] epc : ffffffff80112572 ra : ffffffff80112572 sp : ff2000000000bd30
> [ 0.434177] gp : ffffffff81501588 tp : ff600000018d0000 t0 : ffffffff808cd1a0
> [ 0.434190] t1 : 0720072007200720 t2 : 635f6d656d5f6670 s0 : ff2000000000bdd0
> [ 0.434202] s1 : ffffffff80e17620 a0 : 0000000000000037 a1 : ffffffff814866b8
> [ 0.434215] a2 : 0000000000000000 a3 : 0000000000000001 a4 : 0000000000000000
> [ 0.434227] a5 : 0000000000000000 a6 : 0000000000000047 a7 : 0000000000000046
> [ 0.434239] s2 : 000000000000000b s3 : 0000000000000000 s4 : 0000000000000000
> [ 0.434251] s5 : 0000000000000100 s6 : ffffffff815031f8 s7 : ffffffff8153a610
> [ 0.434264] s8 : 0000000000000060 s9 : 0000000000000060 s10: 0000000000000000
> [ 0.434276] s11: ff6000001ffe5410 t3 : ff60000001858f00 t4 : ff60000001858f00
> [ 0.434288] t5 : ff60000001858000 t6 : ff2000000000bb48
> [ 0.434299] status: 0000000200000120 badaddr: 0000000000000000 cause: 0000000000000003
> [ 0.434394] [<ffffffff80112572>] bpf_mem_alloc_init+0x348/0x354
> [ 0.434492] [<ffffffff80a0f302>] bpf_global_ma_init+0x1c/0x30
> [ 0.434516] [<ffffffff8000212c>] do_one_initcall+0x58/0x19c
> [ 0.434526] [<ffffffff80a0105e>] kernel_init_freeable+0x214/0x27e
> [ 0.434537] [<ffffffff808db4dc>] kernel_init+0x1e/0x10a
> [ 0.434548] [<ffffffff80003386>] ret_from_fork+0xa/0x1c
> [ 0.434618] ---[ end trace 0000000000000000 ]---
>
> [1]: https://lore.kernel.org/20230913135943.3137292-1-houtao@xxxxxxxxxxxxxxx/
> [2]: https://github.com/ClangBuiltLinux/boot-utils/releases
>
> Cheers,
> Nathan
>
> # bad: [98897dc735cf6635f0966f76eb0108354168fb15] Add linux-next specific files for 20230914
> # good: [aed8aee11130a954356200afa3f1b8753e8a9482] Merge tag 'pmdomain-v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/linux-pm
> git bisect start '98897dc735cf6635f0966f76eb0108354168fb15' 'aed8aee11130a954356200afa3f1b8753e8a9482'
> # good: [ea1bbd78a48c8b325583e8c0bc2690850cb51807] bcachefs: Fix assorted checkpatch nits
> git bisect good ea1bbd78a48c8b325583e8c0bc2690850cb51807
> # bad: [9c4e2139cfa15d769eafd51bf3e051293b106986] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git
> git bisect bad 9c4e2139cfa15d769eafd51bf3e051293b106986
> # bad: [4f07b13481ab390108b015da2bc8f560416e48d2] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git
> git bisect bad 4f07b13481ab390108b015da2bc8f560416e48d2
> # bad: [bcfe98207530e1ea0004f4e5dbd6e7e4d9eb2471] Merge branch 'for-linux-next-fixes' of git://anongit.freedesktop.org/drm/drm-misc
> git bisect bad bcfe98207530e1ea0004f4e5dbd6e7e4d9eb2471
> # bad: [95d3e99b1ca8ad3da86c525cc1c00e4ba27592ac] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless.git
> git bisect bad 95d3e99b1ca8ad3da86c525cc1c00e4ba27592ac
> # good: [6836d373943afeeeb8e2989c22aaaa51218a83c6] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc.git
> git bisect good 6836d373943afeeeb8e2989c22aaaa51218a83c6
> # good: [3d3e2fb5e45a08a45ae01f0dfaf9621ae0e439f9] Merge branch 'main' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
> git bisect good 3d3e2fb5e45a08a45ae01f0dfaf9621ae0e439f9
> # bad: [51d56d51d3881addaea2c7242ae859155ae75607] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec.git
> git bisect bad 51d56d51d3881addaea2c7242ae859155ae75607
> # bad: [1a49f4195d3498fe458a7f5ff7ec5385da70d92e] bpf: Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init
> git bisect bad 1a49f4195d3498fe458a7f5ff7ec5385da70d92e
> # bad: [c930472552022bd09aab3cd946ba3f243070d5c7] bpf: Ensure unit_size is matched with slab cache object size
> git bisect bad c930472552022bd09aab3cd946ba3f243070d5c7
> # good: [7182e56411b9a8b76797ed7b6095fc84be76dfb0] selftests/bpf: Add kprobe_multi override test
> git bisect good 7182e56411b9a8b76797ed7b6095fc84be76dfb0
> # good: [b1d53958b69312e43c118d4093d8f93d3f6f80af] bpf: Don't prefill for unused bpf_mem_cache
> git bisect good b1d53958b69312e43c118d4093d8f93d3f6f80af
> # first bad commit: [c930472552022bd09aab3cd946ba3f243070d5c7] bpf: Ensure unit_size is matched with slab cache object size
From 369f2e59cc6c63c3924f654ba3f8491dba58b87b Mon Sep 17 00:00:00 2001
From: Hou Tao <houtao1@xxxxxxxxxx>
Date: Sat, 16 Sep 2023 10:35:52 +0800
Subject: [PATCH] bpf: Check the return value of dma_get_cache_alignment()
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
kernel/bpf/memalloc.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index 1c22b90e754a..c8d2c3097c43 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -6,6 +6,8 @@
#include <linux/irq_work.h>
#include <linux/bpf_mem_alloc.h>
#include <linux/memcontrol.h>
+#include <linux/dma-mapping.h>
+#include <linux/swiotlb.h>
#include <asm/local.h>
/* Any context (including NMI) BPF specific memory allocator.
@@ -958,6 +960,14 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags)
return !ret ? NULL : ret + LLIST_NODE_SZ;
}
+static unsigned int __kmalloc_minalign(void)
+{
+ if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) &&
+ is_swiotlb_allocated())
+ return ARCH_KMALLOC_MINALIGN;
+ return dma_get_cache_alignment();
+}
+
/* Most of the logic is taken from setup_kmalloc_cache_index_table() */
static __init int bpf_mem_cache_adjust_size(void)
{
@@ -992,6 +1002,9 @@ static __init int bpf_mem_cache_adjust_size(void)
size_index[(size - 1) / 8] = index;
}
+ pr_info("==== bpf_mem_cache: KMALLOC_MIN_SIZE %u ARCH_KMALLOC_MINALIGN %u min_align %u\n",
+ KMALLOC_MIN_SIZE, ARCH_KMALLOC_MINALIGN, __kmalloc_minalign());
+
return 0;
}
subsys_initcall(bpf_mem_cache_adjust_size);
--
2.29.2
